Turbomachines, such as turbines and compressors, are often provided with measurement arrangements for measuring several operating parameters. One such operating parameter is the total pressure of the working fluid, i.e. the fluid which flows through the turbomachine. In general terms, according to Bernoulli's principle, the total pressure is the sum of static pressure, dynamic pressure and gravitational head. In most applications, gravitational head can be ignored and the total pressure becomes the sum of dynamic pressure and static pressure.
The total pressure is often a useful parameter for testing purposes on prototype turbomachines. Total pressure can also be a useful control parameter during normal operation of an industrial turbomachine, which can be utilized e.g. for diagnostic purposes or for controlling the turbomachine functionality.
In some applications, the total pressure at the leading edge region of a stationary blade, an inlet guide nozzle, a nozzle guide vane, a return channel blade, a vaned diffuser blade, or other aerodynamic component can be required for control or testing purposes. Total pressure probes must be capable of providing reliable measurements also in case the angle of incidence of the fluid flow deviates with respect to the design angle of incidence. Known means of total pressure measurement at the leading edge of airfoil component include Pitot or Kiel-type probes installed in the desired measurement location, or shielded probes brazed or welded to the outer surface of the airfoil component. These probes are prone to malfunctioning and can accidentally separate from the airfoil component, such that the measurement data are lost.
A need therefore exists for a more efficient and reliable way of measuring total pressure of working fluid at the leading edge of airfoil components in turbomachines.